Fired FBI director James Comey took the stand Thursday in a crucial Senate hearing, repeating explosive allegations that President Donald Trump badgered him over the highly sensitive investigation Russia's meddling in the 2016 election.

In a jam-packed hearing room on Capitol Hill, Comey immediately faced pressure from the Senate Intelligence Committee over whether Trump was obstructing justice in phone calls and meetings they held before the president fired him on May 9.

"This is not how a president of the United States behaves," said Democratic Senator Mark Warner in an opening statement. "Regardless of the outcome of our investigation into those Russia links, Director Comey's firing and his testimony raise separate and troubling questions that we must get to the bottom of."